1. Field of the Invention
This invention relates to moulded plastics tubular couplings and is particularly although not exclusively applicable to tube end supports for locating a tube end in a tube coupling.
2. Background Prior Art
My European Patent Publication No. 0756126 discloses a tube coupling comprising a coupling body having a throughway open at one end to receive a tube, the diameter of the throughway increasing towards said open end at a first step to form a first enlarged diameter portion to receive a tube and a second step to form a second enlarged diameter portion to receive a tube locking device to hold a tube in the coupling body. A thin wall sleeve has one end engageable in the throughway and the other engageable in the tube to be located in the coupling body so that, in use, the sleeve extends from the tube past the first step into the throughway. The sleeve has a sealing engagement with the internal diameter of the tube to prevent leakage between the sleeve and tube and the end of the sleeve projecting from the tube has an annular seal with seals with the throughway in the coupling body to prevent leakage between the sleeve and coupling body.
My European Patent Application No. 99308504.2 discloses a tube end support for locating a tube end in a tube coupling, comprising a sleeve to be received in a tube, an encircling end stop adjacent one end of the sleeve to limit entry of the sleeve into the tube, encircling gripper means on the sleeve to grip on the internal diameter of a tube to hold the tube on the sleeve and a separate annular seal supported by the end and projecting radially outwardly thereof to seal with the internal diameter of a tube coupling in which the assembly of the end support and tube are located.
This invention provides a moulded plastics tubular coupling having a cylindrical surface to engage with a corresponding surface of another component, the surface having an annular recess therein and a flexible annular diaphragm formed in the recess integrally with the coupling and having an outer periphery extending proud of the cylindrical surface to engage and grip the corresponding surface of another component.
In one construction according to the invention the annular recess in the cylindrical surface of the coupling is V-shaped and the flexible diaphragm is formed at the apex of the V to be able to flex towards either side of the v when the coupling is engaged with another component.
In a preferred form of the invention the recess and diaphragm are formed on the outer cylindrical surface of the coupling to engage an inner surface of a component to encircle the coupling.
More specifically, in the case where the coupling is intended to receive an end of a length of tubing, the coupling may have a sleeve portion having said recess and diaphragm formed around the outer surface of the sleeve portion partway along the sleeve; a tapered portion at one end of the sleeve to facilitate insertion of the sleeve into an end of a length of tubing and an end stop at the other end of the sleeve to limit the insertion of the sleeve into the tube.
By way of example the end stop may comprise an annular head formed at said other end of the sleeve projecting outwardly of the sleeve.
In one specific arrangement the head may be formed with means to grip/seal with an encircling component in which the sleeve is engaged
For example the head may have an encircling groove in which an O-ring or similar seal is mounted.
In a further arrangement the outer surface of the head may have an annular recess in which a further flexible diaphragm is formed integral with the head and projecting proud of the outer surface of the head to engage and lock the head in the bore of a component in which the coupling is located.